Multiple Cascaded Backup Process

1. A computer program product on a non-transitory computer readable medium for handling a backup process, the product comprising instructions for: receiving an instruction initiating a new backup from a source volume to a target volume using a specified backup process type comprising one of a clone and snapshot, wherein the clone comprises a point-in-time copy, and wherein the target volume holds a complete copy of data on the source volume; determining, from a computer readable medium maintained by a storage volume controller, whether there is an existing cascade of volumes using the specified backup process type including the source volume of the new backup, wherein a cascade includes a cascade source volume from which data is written to at least one cascade target volume using a cascade backup process type comprising one of the snapshot and clone backup process types; modifying the determined existing cascade using the specified backup process type to include the target volume of the new backup in response to determining the existence of the cascade using the specified backup type; and creating a new cascade using the specified backup process type of the new backup including the source volume and the target volume of the new backup in response to determining that there is not the existing cascade using the specified backup process type, wherein a cascade extending from one source volume will only copy data to target volumes in the cascade using the cascade backup process type with which the target volume was created so that data from a clone backup process type is not copied to a target volume created using the snapshot backup process type and vice versa.

2. The computer program product of claim 1 , wherein modifying the cascade to include the target volume of the new backup further comprises: including the target volume of the new backup between the cascade source volume and the cascade target volume linked to the cascade source volume in the cascade order in response to determining that the source volume of the new backup is the cascade source volume.

3. The computer program product of claim 1 , wherein modifying the cascade to include the target volume of the new backup further comprises: including the target volume of the new backup between a first cascade target volume linked to the cascade source volume and a second cascade target volume linked to the first cascade target volume in response to determining that the source volume of the new backup is the first cascade target volume.

4. The computer program product of claim 1 , wherein two cascades for the two backup process types have a common cascade source volume and at least one common cascade target volume linked to the cascade source volume.

5. The computer program product of claim 4 , wherein a write to one cascade target volume in one of the two cascades causes data to be written from the common cascade source volume to the cascade target volumes in the two cascades.

6. The computer program product of claim 1 , wherein creating the new cascade comprises: in response to determining that there is an existing cascade of a different backup process type than the new backup and that the existing cascade includes a cascade source volume and a cascade target volume that is the source volume of the new backup, forming the new cascade, using the specified backup process type, to include the cascade source volume and the cascade target volume of the existing cascade and to link the target volume of the new backup to the cascade target volume of the existing cascade.

7. The computer program product of claim 1 , further comprising identifying the specified backup process type of the new backup as a restore process intended to restore a complete copy of the source volume on the target volume and starting a new cascade of the target volume from the source volume.

8. The computer program product of claim 1 , wherein the backup process types further comprise a fractional backup process and a full backup process, further comprising: detecting that a backup process type of a source volume to a target volume identified as the fractional backup process type is stopped; and stopping all backup processes to target volumes that follow the target volume in the stopped backup process in at least one cascade of the fractional backup process type and the full backup process type.

9. A system for handling a backup process comprising: a plurality of volumes; and a storage volume controller connected to the volumes, wherein the storage controller performs operations, the operations comprising: receiving an instruction initiating a new backup from a source volume to a target volume using a specified backup process type comprising one of a clone and snapshot, wherein the clone comprises a point-in-time copy, and wherein the target volume holds a complete copy of data on the source volume; determining, from a computer readable medium maintained by a storage volume controller, whether there is an existing cascade of volumes using the specified backup process type including the source volume of the new backup, wherein a cascade includes a cascade source volume from which data is written to at least one cascade target volume using a cascade backup process type comprising one of the snapshot and clone backup process type; modifying the determined existing cascade using the specified backup process type to include the target volume of the new backup in response to determining the existence of the cascade using the specified backup type; and creating a new cascade using the specified backup process type of the new backup including the source volume and the target volume of the new backup in response to determining that there is not the existing cascade using the specified backup process type, wherein a cascade extending from one source volume will only copy data to target volumes in the cascade using the cascade backup process type with which the target volume was created so that data from a clone backup process type is not copied to a target volume created using the snapshot backup process type and vice versa.

10. The system of claim 9 , wherein modifying the cascade to include the target volume of the new backup further comprises: including the target volume of the new backup between the cascade source volume and the cascade target volume linked to the cascade source volume in the cascade order in response to determining that the source volume of the new backup is the cascade source volume.

11. The system of claim 9 , wherein modifying the cascade to include the target volume of the new backup further comprises: including the target volume of the new backup between a first cascade target volume linked to the cascade source volume and a second cascade target volume linked to the first cascade target volume in response to determining that the source volume of the new backup is the first cascade target volume.

12. The system of claim 9 , wherein two cascades for the two backup process types have a common cascade source volume and at least one common cascade target volume linked to the cascade source volume.

13. The system of claim 12 , wherein a write to one cascade target volume in one of the two cascades causes data to be written from the common cascade source volume to the cascade target volumes in the two cascades.

14. The system of claim 9 , wherein creating the new cascade comprises: in response to determining that there is an existing cascade of a different backup process type than the new backup and that the existing cascade includes a cascade source volume and a cascade target volume that is the source volume of the new backup, forming the new cascade, using the specified backup process type of the new backup, to include the cascade source volume and the cascade target volume of the existing cascade and to link the target volume of the new backup to the cascade target volume of the existing cascade.

15. The system of claim 9 , further comprising identifying the specified backup process type of the new backup as a restore process intended to restore a complete copy of the source volume on the target volume and starting a new cascade of the target volume from the source volume.

16. The system of claim 9 , wherein the backup process types further comprise a fractional backup process and a full backup process, further comprising: detecting that a backup process of a source volume to a target volume identified as the fractional backup process type is stopped; and stopping all backup processes to target volumes that follow the target volume in the stopped backup process in at least one cascade of the fractional backup process type and the full backup process type.

17. The computer program product of claim 1 , wherein the backup process types include a full backup process to make a complete copy of the source volume on the target volume and a fractional backup process to make a copy of data changed on the source volume on the target volume.

18. The computer program product of claim 1 , wherein the backup process types comprise a fractional backup process and a full backup process, wherein the operations further comprise: detecting that the full backup process of a source volume to a target volume identified is stopped; and stopping all backup processes to target volumes that follow the target volume in the stopped backup process in at least one cascade of the fractional backup process type.

19. The system of claim 9 , wherein the backup process types include a full backup process to make a complete copy of the source volume on the target volume and a fractional backup process to make a copy of data changed on the source volume on the target volume.

20. The system of claim 9 , wherein the backup process types comprise a fractional backup process and a full backup process, wherein the operations further comprise: detecting that the full backup process of a source volume to a target volume identified is stopped; and stopping all backup processes to target volumes that follow the target volume in the stopped backup process in at least one cascade of the fractional backup process type.